Silvanus phillips thompson



(No Model.)

S. P. THOMPSON.

ELEGTRIG CABLE. 7 No. 568,964. 6 P6666666 0013. 6, 1896.

1 J REWTM 55mm" a d b e I 1 l 31 WJ A UNITED STATES,

PATENT Qrricn,

SILVANUS PHILLIPS THOMPSON, OF LONDON, ENGLAND.

ELECTRIC CABLE.

SPECIFICATION forming part of Letters Patent No. 568,964, dated October6, 1896.

Application filed December 19, 1896.

Renewed August 11, 1896. 8erial No. 602,457. tNomodel.)

Patented in England December 21, 1891, No. 22,804, July 4, 1898,1I0.18,064, and December 19, 1893, No. 13,581; iuPranceJune 20,1892,No222,460, and December 18, 1893,1I0. 284,763; in GermauyOc'tcber 23,1892, No. 86,013; in India A ri125,1898, N0. 320, and August 17,1894,No.18,- in Spain 8eptember 4,1893, No, 13,896, and April 10, 1894, No.15,306; in Brazil February '7, 1894, No. 1,686 3 in Ceylon August 22,1894, N0. 448, and in Straits Settlements December 14, 1895.

To all whom it may concern.-

Be it known that I, SILVANUS PHILLIPS THOMPSON, a citizen of GreatBritain, residin g at East Ilampstead, London, in the county of London,England, have invented certain new and useful Improvements in ElectricCables, (patented in the United Kingdom, No. 22,304, December 21, 1891,No. 13,064, July 4, 1893, and No. 13,581, July 13, 1894, antedatedDecember 19, 1893; in France, No. 222,460, June 20, 1892, and No.234,763, December 13, 1893; in Germany, No. 86,013, October 23, 1892; inSpain, No. 13,896, September 4, 1893, and No. 15,306, April 10, 1894; inBrazil,No.1, 686,February 7, 1894; in India, No.320, April 25, 1893, andN0. 18, August 17, 1894; in Ceylon, No. 443, August 22, 1894, and inStraits Settlements December 14,1895,) of which the following is adescription, reference being had to the accompanying drawings, and tothe letters of reference marked thereon.

My invention relates to improvements in submarine electric cables, andmore particularly to means for overcoming the retardation of signalstherein.

In my applications for Letters Patent, Serial Nos. 440,672 and 440,673,filed July 20, 1892, I have shown, described, and claimed methods andapparatus having this end in. View. The present application, however,differs therefrom in certain important particulars, as will more fullyhereinafter appear.

The present application discloses means for adapting my genericinvention to existing types of submarine electric cables, whether thesame contain one or two continuous conductors, and by said means I amenabled to increase their speed of signaling and also to adapt them foruse as telephonecircuits. y

In the case of 'a sin gle-wire cable I join onto the conductors atintervals compensating branches of the hereinafter-described kind, whichfor telegraphic purposes may be as much as two hundred or even fivehundred miles apart and for telephonic purposes as near together astwenty or forty miles, according to the nature and total length of thecable.

Each compensating branch consists of a short conductor in metallicconnection with the conductor within the cable and thoroughly insulatedwith the usual coatings and sheathings, so as to prevent the admissionof water to the main cable and to the insulated part of the branch, thebranch being provided at its extremity with an exposed metallicterminal, which, being in contact with the water, forms an earth-plate,or in lieu thereof being connected to the iron sheathing of the cable,so that the same may act as earth or earth-plate. The branch possessesresistance and self -induction and is so proportioned that it forms aleak on the cable of a definite and determined kind, that is to say, itconstitutes a leak differing from an accidental leak in that itpossesses a definite resistance and a definite selfinduction, both ofwhich qualities remain practically constant and are not liable to changeby corrosion, as accidental leaks will do.

In the drawings, Figure 1 is a diagrammatic view of a single wire cableand branches. Fig. 2 is an enlarged detail show ing a method of securingthe branches to the cable. Fig. 3 shows diagrammatically a twowire cablewith branches extending across. Fig. 3 shows diagrammatically a two-wirecable with a piece of special cable joined in. Fig. 4 showsdiagrammatically a two-wire cable with alternately-arranged compensatingbranches. Fig. 5 shows a two-wire cable, each conductor provided with abranch. Fig. 6 is an enlarged detail of one form of exposed terminal.Fig. 7 is an enlarged detail of another form of exposed terminal.

If the compensating branch possesses a high resistance, for example,from ten thousand to one hundred thousand or more ohms, even withou t any appreciable self-ind uction, it will accelerate the speed ofsignaling; but if it also possesses a coefficient of self-induction, sayfrom as little as one millihenryto as much as one hundred henries, itwill act better as a compensator, because such self-induction will notonly increase its apparent resistance, but will also actually in somemeasure operate favorably as a negative capacity to counteract thecapacity of the cable in the parts within some miles on both sides ofthe point where it is attached.

Compensating branches having the desired property will resembleoutwardly portions of ordinary submarine cable, but inwardly difl'crsomewhat. If aniron wire is ei'nployed in place of the ordinary copperwire, it will have both a higher resistance and a higher self-induction.If a german-silver wire is used, it will have higher resistance, but itwill not have a higher self-induction unless it is either coiled aroundan insulated iron core (which may itself be a stranded bundle of ironwire insulated) or is itself rewound with iron outside to increaseitsself-indut'rtion. A compensating branch live miles long, if made of astraight insulated iron wire one twentylii'th of an inch in diameter,insulated and overwonnd with live layers of iron wire each about afortieth of an inch in diameter, will have approximately a resistance ofeight hundred ohms and a sell-induction of three hundred to four hundredmillihenries. F or rapid signalingit will have a virtual resistance manytimes greater than its actual resistance. If the iron wire, instead ofbeing straight, is lightly insulated and coiled in a spiral around awellinsulated stranded iron wire as core, and the whole is then wellinsulated externally and incloscd in a proper sheath, it will serve as acompensating branch of higher resistance.

One end of each such compensating branch will be jointed into the cable,Fig. 2,the insulating material around it being carefully jointed withthat surrounding the cable and must be continuous with it. The other endwill be connected to a suitable earth-plate or simi lar organ suitableto be immersed in the sea or to the iron sheathing of the cable. If aniron wire is used as a conductor in the compensating branch, it may bejoined at the end where it is to unite with the earth-plate to astotiter-stranded iron wire, and this again to a still stoutor-strandediron cable, a portion of which may be submerged exposed or it mayterminate in the iron sheathing of the cable; or an iron plate or ballor shell, Figs. t3 and 7, may be employed, the same being several feetin diameter, giving also a large surface and of considerable thickness,so tha-tthe corrosion may be spread over many years, but in all casesavoidingany exposure to the sea of any two metals which would set upgalvanic corrosion mutually by contact. All such joints near the sea endshould be prefer ably made by electric welding. If the last few feet ol.the conductor in the compensting branch be constituted of a strandedplatinum wire jointed onto the iron or german-silver or other wire usedin the branch, the end of the stranded platinum wire may be brought outand welded to a platinum plate, Fig. (5, to serve as an earth-plate. Inall cases the insulating covering must be waterproolt' and be carriedright down to the mass of metal which serves as earth-plate.

In the cases where the compensating branches are to be applied to anexisting cable containing twoinsulated conductors, they will be jointedin at one end to a pointon one of the two conductors, and at the otherend they will be jointed onto the other conductor, Fig. 23, therebyconstituting a bridge across from one to the other conductor. II the twopoints chosen on the respective conductors are near together, thecompensating branch or bridge must have both high resistance and highsellfinduction; but it the two points chosen on the respectiveconductors are far apart, then the compensating branch or bridge neednot be either of such high resistance or self-induetion.

For example, it the two conductors ol the cable are stranded copperwires, each consist;- ing of seven wires, each being one-forticth of aninch in diameter, and the compeusat ing branch used as a bridge be tenmiles long, consisting of an iron stranded wire made up of three wires,each onefortiel'h of an inch in diameter, such compensating branch orbridge should be joined at its ends to the two conductors, respectively,at points ten miles apart. In the case of cables containing twoinsulated conductors it is also possible to use compensating branchesnot as bridges from wire to wire, but as branches from the cable to thesea,with earth-plates, as previously described, lor single-wire cables,but in such case the compensating branches should be connected to thetwo coud uctors alternately: namely, lirst, from one conductor of thecable to the sea; then at an intervalolj' ten or twenty or more milesfrom the other conductor of the cable to the sea; then at anothersimilar interval from the iirst conductor to the sea, the; and in suchcase also there is no need for the compensating branches so used to haveeither a very high resistance or a very high self-induction. Forinstance, a branch one mile long, consisting of a stranded iron wiremade up oi three wires each one twenty- Jifth of an inch in diameter,suitably insulated and connected to a suitable earthq lalc, may bejointed in alternately, as describedabove, at intervals of ten, twenty,or lii'ty miles, or more; or two such may be inserted at iii'ty or onehundred miles apart near the middle of a long cable to increase itsspeed of signaling; or, again, at the middle of a long two wire cable asingle bridge f, Fig. I may be inserted from wire to wire, its endsbeing, for example, inserted at two points twenty miles apart; or aspecial piece oi cable of much smaller length, containing both thebridgewire f and the two parallel conductors from 4.0 to y, may beinserted in the middle of the two-wire cable.

Iliefcrring to the drawings, Fig. 1 represen is the conductor oi asingle-wire cable, to which are electrically connected. branch wires 0I) (2, connected with earth-plates E. The branch wires and conductor A.are thoroughly insw latcd, the earth plates E alone being exposed.

The insulation is in this instance omitted for convenience.

A, in Fig. 2, is an enlarged detail illustrating means for lashing thebranch wires to the main cable at a point beyond its junction with saidcable in order to relieve the strain and possible leakage at the joint.a is the branch, and A is a suitable lashing uniting the main cable andthe branch.

Fig. t shows diagrammatically a two-wire cable containing conductors Aand B, separately insulated and contained within a single externalsheath. In this instance branch wires a I) extend from the cable A,while similar branches (1 e extend from the cable B. The branchconductors are the same in structure in this instance as in Fig. 1, butwhere the cable contains two wires the branches are taken alternatelyfrom opposite conductors, and although said branches are shown in closeproximity it must be understood that they are to be placed more or fewermiles apart, according to circumstances.

Fig. 3 shows a two-wire cable A B, joined by a compensating branch f,extending from one conductor to another, said branch extending over aconsiderable distance and so proportioned as to equalize theelectrostatic conditions of the conductors.

Fig. 3 shows in detail and conventionally a piece of special cable fromac to y, joined into the main cable and provided with bridgeconductor f,which possesses both high resistance and self-induction.

Fig. 5 illustrates, diagrammatically, the application of a single pairof compensating branches g g near the middle of a long cable.

Fig. 6 shows one form of plate in which the cable a, forming the branch,is spread at its end and each strand 1' thereof soldered or otherwisemetallicallyconnected with an extended exposed plate F of the same metalas the end of the branch cable, which is preferably of platinum, fordurability. The extremities, at least. of the strands of the branchconductor should also be of platinum, care being taken that the jointbetween the platinum extremities of the branch conductor and theremainder thereof. especially if of different material. be securelyinclosed within waterproof insulating material I.

A convenient and durable form of terminal for the branch conductors isshown in Fig. 7, in which the extremity of the branch conductor h issecured to a stem G, provided with an opening to facilitate handling thesame, said exposed stem being connected with a ball H of the same metalas the stem.

In View of the foregoing description it will be apparent that the formand nature of the earth-plate or exposed terminal of the branchconductors may be made in various forms and of various materials. Itherefore do not limit myself to any specific detail in this connection.It is also obvious that the branch conductors may be arranged in Variousdifferent ways consistent with the description thereof.

Having described my invention, what I claim is 1. An electric cable forsubmarine use consisting of a main copper conductor continuous from endto end, surrounded by an insulating-sheathing and furnished at regularintervals along its length with branch conductors all of equal highresistance and equal self-induction, each such branch conductorconsisting of a metallic core jointed into the main conductor and of aninsulating-sheath extending all along its length and continuous with theinsulating-sheath of the main conductor, the outer end of each suchbranch being earthed.

2. The combination with a single-conductor electric cable forsubmarineuse of one ormore compensating branches, each such branch consisting ofan insulated conductor having both a higher resistance and a higherselfinduction than the entire length of the main conductor jointed intothe cable at some intermediate point and constituting an integral partof the cable.

3. The combination with an electric cable for submarine use having twoinsulated conductors, of one or more compensating branches, each suchbranch being jointed in as a bridge across from one conductor to theother conductor, such branch being surrounded throughout its entirelength with insulating material which is jointed into and continuouswith that of the cable.

4. The combination with an electric cable having two insulatedconductors, of an intermediate piece of special cable containing also abridge-wire possessing both self-induction and high resistance, theinsulating material surrounding said bridge-wire being continuous withthe insulation surrounding the two insulated conductors.

5. The combination with. an electric cable having twoseparately-insulated conductors running therethrough side by side of oneor more compensating branches, each such branch being of higherresistance and selfinduction and jointed on as a leak from one of theconductors to the sea, said branches being taken at regular intervalsand alternately from the two conductors.

In testimony whereof I hereto affix my signature in presence of twowitnesses.

SIINANUS PHILLIPS THOMPSON.

\Vitnesses:

K. Dovn, SYDENHAM KEEN.

